It's not necessary to convert it to qemu image file to be able to access it.
Although it might save some space - leave the original untouched, make copies converted to qcow2.
as you want to analyze data, you should not change anything or boot from this image. boot from another system (e.g. a Linux live cd) and mount the disk.
by doing this, you can also analyze the boot problem (missing bootloader, MBR).